Azimuth instrument

The Azimuth instrument was a telescope-like device used by the United States to triangulate the positions of Kriegsmarine vessels during World War II.

History
Azimuth instruments were the principal means of aiming the coastal artillery of the United States during World War II. A directional reading from the scope on an enemy ship would determine its angle (azimuth) from the known location of the control tower, and when two or three azimuths were plotted from different towers, the position of the target could be pinpointed. With azimuth readings taken every 30 seconds, it could be predicted where the ship would be in the next 30 seconds, and the information would be relayed to the artillery. The artillery could than triangulate its fire on the enemy ships.

These instruments were employed by the US Coast Guard to spot Nazi Germany's Kriegsmarine submarines or battleships and guide artillery strikes on them. The Kriegsmarine proved to be a tough enemy during the Second Happy Time of January to August 1942, when America was welcomed to the Battle of the Atlantic by tough attacks by U-boats that sunk 609 ships with only 22 U-boat losses. An Azimuth instrument from World War II is maintained on the top floor of Fire Control Tower No. 23 in Cape May, New Jersey.